Just a few years ago, President Obama refused to shop at Wal-Mart. But his wife now has other ideas.

First lady Michelle Obama joined executives from the big-box behemoth on Thursday to announce a new program to promote more healthful foods. The move was part of her signature campaign to fight childhood obesity, and Wal-Mart pledged to reduce sodium and sugar and eliminate trans fats in the packaged foods it sells to roughly 140 million customers each week - or, possibly now 140,000,002.

"When I see a company like Wal-Mart launch an initiative like this, I feel more hopeful than ever before," the first lady said in a speech at THEARC in Southeast Washington in front of crates of fresh produce. "We can improve how we make and sell food in this country."

The announcement amounted to a very public display of affection for a company that had long been a thorn in the side of Democrats. Five years ago, Wal-Mart was in the midst of a bruising battle with labor groups that accused it of paying low wages and providing stingy health benefits. Then-Sen. Hillary Rodham Clinton returned a campaign contribution from the company, citing "serious differences." Michelle Obama resigned from the board of a Wal-Mart supplier during her husband's campaign.

And Obama himself told supporters at an AFL-CIO forum in 2007 that he would not shop at Wal-Mart.

"Lots has happened since 2007," Obama press secretary Robert Gibbs said Thursday. "I think we're all in a different time."

At least it won't be hard for the first family to find a Wal-Mart. The retailer has announced plans to build four stores in the District as part of its bid to move into more urban areas after saturating rural and suburban America. Several D.C. Council members, including Marion Barry (D-Ward 8) and Chairman Kwame R. Brown (D), attended Thursday's event.

And in the Obamas' home town of Chicago, Wal-Mart has made inroads as well. The retailer opened its first store in the city in 2006 after heated debate over wages and benefits, and last year it won approval for a second location. It is now pursuing its first store in New York City and hopes the first lady's support will help win over opponents in these cities and Washington.

"We'll carry forward that message," said Leslie Dach, executive vice president of corporate affairs for Wal-Mart.

For Michelle Obama, Wal-Mart represents a key ally, albeit a controversial one. It is the biggest grocer in the country and works with a vast network of more than 60,000 suppliers. One move by Wal-Mart can ripple throughout the industry, and the company has grown increasingly bold in tackling complex social and political issues.

"We are obviously conscious about where we walk and who we walk with," said Sam Kass, assistant White House chef and coordinator of food initiatives. "But it was clear that this is potentially transformative."

In recent years, Wal-Mart has reached out to Democrats. During the debate over health care, it broke ranks with business groups by supporting the controversial mandate for employers in Obama's health-care legislation. It has emerged as a leader in sustainability and carbon reduction, improving fuel efficiency for its supply trucks and vowing to eventually produce zero waste.

Healthful foods skyrocketed to the top of the company's priority list once the first lady made it hers by launching the Let's Move campaign. Conversations between Wal-Mart and the East Wing began about a year ago. Company leaders Thursday cited Michelle Obama as the "catalyst that helped make today's announcement a reality."

"You can't do work in this area without reaching out to the first lady's office," Dach said.

Under the program, Wal-Mart vowed to reduce sodium by 25 percent and sugars by 10 percent in thousands of packaged foods by 2015. The retailer said it has already met the goal in as much as a quarter of the products in its private-label brand, Great Value.

The company plans to tag products that meet the goals so customers can easily identify them. It also says it will lower prices on healthful foods, such as whole-wheat pasta, so that they cost the same as traditional versions. Several of these initiatives have been underway for years at food manufacturers such as Kraft as well as smaller retailers.

Some things at Wal-Mart haven't changed. It remains a staunch opponent of the Employee Free Choice Act, also known as "card check," that would make it easier for workers to organize. The issue has fallen out of the spotlight recently, but it is still a divisive issue between Wal-Mart and labor groups. Meanwhile, the Supreme Court is considering whether to certify a class-action sex-discrimination lawsuit against the company, which would make it the largest gender-bias case in U.S. history.

"We can't afford to have a case of amnesia about Wal-Mart's business practices," said Jennifer Stapleton, assistant director of the United Food and Commercial Workers International Union's campaign against the retailer. "If the Obama administration is serious about creating good jobs in this country . . . then it needs to use its bully pulpit to challenge Wal-Mart and other corporations to be more responsible employers."

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